De-inking printed waste cellulosic stock with nonionic detergent and a polyol



y 9, 1968 R. H. ILLINGWORTH 3,

DE-INKING PRINTED WASTE CELLULOSIC STOCK WITH NONIONIC DETERGENT AND APOLYOL Original Filed Aug. 17, 1966 WATE R SOURCE DETERGENT REACTORWASTE PAPER CH EST DILUTION WASHER 8. THlCKENER (3-STAGE) ACIDIF'ICATIONACID WASTE EFF'LUENT THICKENER WEB FORMING INVENTOR. ROBERT H.ILLINGWORH BY May, I a/40! I PM ATTORNEYS United States Patent 3,392,083DE-INKING PRINTED WASTE CELLULGSEC STOCK WllTH NONIONIC DETERGENT AND APOLYOL Robert H. Illingworth, Madison, N.J., assignor to Garden StatePaper Company, Inc., Garfield, N.J., a corporation of New JerseyContinuation of application Ser. No. 573,127, Aug. 17, 1966. Thisapplication July 3, 1967, Ser. No. 651,048 13 Claims. (Cl. 1625)ABSTRACT OF THE DISCLOSURE A method of de-inking waste printed paper bypulping the waste paper with a polyol such as a glycol and a nonionicsurface active agent containing a polyoxyalkylene chain of at least twoalkenoxy groups and derived from alkyl phenolic compounds in which thetotal number of alkyl carbon atoms is between 4 and 24.

This application is a continuation of copending application Ser. No.573,127, filed Aug. 17, 1966, now abandoned, and a continuation-in-partof copending application Ser. No. 193,448, filed May 7, 1962. Theaforesaid application Ser. No. 573,127 was a continuation of andcopending with application Ser. No. 294,410, filed July 11, 1963, nowabandoned. The aforesaid application Ser. No. 193,448 was acontinuation-in-part and copending with the following applications, nowabandoned: Ser. No. 84,908, filed Jan. 25, 1961, Ser. No. 95,722, filedMar. 14, 1961, and Ser. No. 95,723, filed Mar. 14, 1961.

This invention relates to improvements in de-inking printed wastecellulosic stock.

It is an object of the present invention to-provide improved methods andagents for de-inking printed cellulosic material to produce a pulp thatcan be readily and economically handled on conventional paper makingmachines to produce newsprint, magazine or book stock.

It is another object of this invention to provide irnproved processesand agents for de-inking waste printed paper to produce a pulp at leastsubstantially equal, and

often superior, in brightness, color and strength to that of virginpulp.

Still another object of this invention is to provide improved agents andmethods capable of de-inking a wide variety of waste printed paper,regardless of the type of ink or method of printing originally employedto produce the printed paper.

Other objects of the present invention will in part be clear and will inpart appear hereinafter.

Commercial conversion of waste newspaper, magazine and other types ofprinted waste cellulosic stock to a pulp capable of reuse in formingpaper or other cellulosic products has been a much sought after goal inthe paper industry.

Although many processes for de-inking such printed cellulosic materialhave been heretofore proposed, in general, these have not provedcommercially satisfactory. Many of these processes for example, whentested on a commercial scale with the general run of waste newspaper andjunk, fail to yield a pulp suitable for reuse as newsprint, magazine orbook stock. The failure may be attributable to the fact that many ofthese processes drive a significant portion of the ink particles intothe cellulosic fibers, thereby rendering the pulp gray andunsatisfactory for use except for the manufacture of low grade papermaterials, for example, low grade packaging cartons. Other of theseprocesses are so expensive, time-consuming, laborious and complicatedthat they are simply not economically feasible.

3,392,983 Patented July 9, 1968 In the copending applications referredto hereinbelow, there are described processes for de-inking wastenewspaper, magazines and other types or printed waste cellulosic stockwhich utilize, as the active de-inking agent, certain nonionicdetergents, e.g., ethylene oxide adducts of alkyl phenols.

Such nonionic detergents, by themselves, give satisfactory de-inkingresults when used with the general runof-the-mill waste newspaper andmagazine stock produced; for example, standard planographic, e.g.,offset, printing techniques and inks. With certain waste printedcellulosic stock, however, e.g., paper printed by intaglio such asrotogravure techniques and inks, nonionic detergents of the typespecified above and in the copending applications do not, by themselves,accomplish a completely satisfactory de-inkin job.

As will be readily apparent, in commercial tie-inking, it would behighly advantageous if the process would be able to handle a widevariety of waste printed stock, regardless of the type of ink orprinting technique originally used in producing the waste printed paper.Otherwise, a costly and time-consuming paper separation step would haveto precede de-inking. The economics of paper de-inking are such that apaper separation or classification step could well spell the differencebetween success and failure.

According to the present invention, it has been discovered that improvedde-inking results may be realized by utilizing as the active de-inkingagent the combination of (l) a nonionic detergent, and (2) a polyol.

This combination of ingredients, when used as described herein, has beenfound to be effective in de-inking all types of waste printed cellulosicstock, regardless of the type of ink or printing technique originallyutilized in producing the paper.

The polyols suitable for use are those compounds having more than onehydroxyl (-OH) group, each of which is attached to separate carbon atomsof an aliphatic skeleton. This group includes glycols, glycerol,pentaerythritol, and also such compounds as trimethylolethane,trimethylolpropane, 1,2,6-hexanetriol, sorbitol, inositol, and the like.The dihydric polyols, e.g., the glycols, such as ethylene glycol,diethylene glycol, trimethylene glycol, propylene glycol, dipropyleneglycol, and the like, are especially suitable. Of the glycols, ethyleneglycol is preferred.

The nonionic detergents suitable for use may be described aswater-soluble synthetic nonionic surface active agents containing apolyoxyalkylene chain of at least two alkenoxy groups, and derived fromalkyl phenolic compounds in which the total number of alkyl carbon atomsis between 4 and 24.

The above defined nonionic surface active agents operative in theinstant invention may be more specifically represented by the generalformula wherein R represents the residue of a suitable alkyl phenol, Rrepresents hydrogen or lower alkyl, and n has a value from 2 to or moreand usually from about 4 to 30. Compounds of this type are well known inthe art and are disclosed along with suitable methods for theirpreparation in US. Patent 2,946,921. In general, they may be obtained bycondensing a polyglycol ether containing the required number of alkenoxygroups or an alkylene oxide such as propylene oxide, butylene oxide, orpreferably ethylene oxide, with a suitable alkyl phenol. The amount ofalkylene oxide condensed with the alkyl phenol, i.e., the length of thepolyoxyalkylene chain, will depend pri marily upon the particularcompound with which it is condensed. As a convenient rule of thumb,approximately 1 mole of alkylene oxide should be employed for each twocarbon atoms in the alkyl phenol. However, the optimum amount ofalkylene oxide may readily be determined in any particular case bypreliminary test and routine experimentation.

An especially suitable nonionic detergent is an ethylene oxide adduct ofdodecylphenol having a formula corresponding to that indicated above,wherein n is between about 8 and 15. Another particularly suitablenon-ionic detergent is a condensation product of nonyl-phenol andethylene oxide having the structural formula wherein n is an integerbetween 8 and 15.

The amount of nonionic detergent and polyol employed should be carefullycontrolled. Based on the weight of paper, the amount of each of thesematerials may vary between about 0.1 and 3.0 percent. Especially goodresults are obtained when about 1 and 2.5 percent by weight of paper ofeach material is employed, and this amount is preferred.

The relative proportion of nonionic detergent to polyol may be variedover fairly wide ranges. In general, the weight ratio of nonionicdetergent to polyol may vary from about 10:1 to 1:10, but preferably itis about 2:1 to 1:2.

Preferably, the nonionic detergent and polyol are admixed, and theadmixture added to water to form the deinking solution.

The combined de-inking agent constitutes a part of the presentinvention, and, as indicated above, comprises compositions satisfyingthe following formula:

Parts by weight Nonionic detergent 10 to 1 Polyol 1 to 10 Thetemperature of the de-inking solution may vary anywhere from roomtemperature, e.g., 40 to 70 F., up to the cloud point or volatilizationtemperature of the nonionic detergent, although preferably the de-inkingsolution is employed at room temperature.

Best results are achieved with the de-inking solutions described hereinwhen they are alkaline in pH and it therefore is desirable that analkali be included therein. Although any suitable alkali or alkalineearth metal hydroxide or salt may be employed, the alkali metalhydroxides and salts, such as sodium hydroxide, potassium hydroxide,soda ash and the like are preferred. Enough of the alkali should beadded to maintain the pH of the de-inking solution between about 7.0 and10, or even higher, and preferably at least about 7.1.

In preparing the de-inking solution, water is charged to the reactor orpulper and the active de-inking agents described hereinabove added. Thede-inking agents are preferably added to the water prior to the additionof the Wastepaper or junk.

To the resulting solution is added the printed paper, scrap or junk. Theprinted cellulosic charge may, if desired, be shredded by appropriatemeans prior to treatment. This, however, is not necessary, and the wastematerial may be added to the treating solution without shredding orwithout any subdivision in size whatsoever. It is one of the advantagesof this invention that costly shredding or pulping techniques prior tode-inking need not be employed. Thus, the waste material to be de-inkedis preferably added to the treating solution in its naturally drycondition, i.e., without being subjected to moisture or water other thanthat which is normally present in the atmosphere. Although de-inkingwill occur if the Waste material is first slurried or pulped in water,in general it has been found that the results achieved are inferior tothose obtained when the waste material is added to the treating solutionin its naturally dry condition, i.e., in equilibrium with its naturalatmospheric environment. Although not wanting to be restricted to thisinterpretation, it appears that wetting the waste material with waterprior to subjecting it to the chemical treatment described herein has atendency to set the ink and make it more difficult to remove from thecellulosic fibers. The amount of the scrap or junk added to the treatingsolution should be controlled. In general, the percent of cellulosicmaterial by Weight of the aqueous treating solution should be below 10percent and preferably below 6.0 percent, or between about 4.0 and 6.0percent. Good results are obtained when the de-inking solution containsabout 5 to 5.5 percent by Weight of paper and this value appears to beoptimum. The scrap is retained in the treating solution untilsubstantial defiberization takes place. Depending upon the degree ofagitation in the reactor, the time in the reactor may vary between about10 and 50 minutes, and is usually between about 20 and 40 minutes.

Following treatment, the defibered material is dropped to a chest orother suitable reservoir, after which it is diluted with water to asolid content of between about 0.5 and 1.5 percent, preferably about 1.0percent, based upon the solution weight.

Following dilution, the pulp is separated from the solution and washedand thickened by well known methods. The resulting pulp is thenacidified to a pH of between about 4 and 6.5, preferably between about4.5 and 5.5, thickened and then formed into a web.

This acidification step has been found to significantly increase thebrightness of the paper produced from the recovered pulp, and also voidsthe necessity of bleaching the pulp. Moreover, it has been discoveredthat acidification tends to set any residual ink particles which may bepresent, thereby preventing such particles from coming off on the feltsand rolls during the web forming step. Such residual ink particles inthe past have been found to create considerable difficulty andaggravation during web forming.

The recovered stock may be blended with fresh virgin sulfate or sulfitestock, or with additional recovered stock to rlnake cellulosic articles,such as newspaper, and so fort A suitable arrangement for carrying outthe de-inking process is illustrated in the accompanying drawing, whichis a flow sheet of the steps in a particularly suitable process.

As indicated in the drawing, water from an appropriate source is chargedto a suitable reactor or pulper. The reactor or pulper used in theprocess is equipped with a stirrer or agitator of any appropriate shapewhich will agitate and defiber the cellulosic material. If desired,baifie plates may be attached to the interior of the reactor to assistthe agitation action.

After the water has been charged to the reactor, the combined de-inkingagents described herein are added and agitation continued until theagents are dispersed and/or dissolved.

Wastepaper, junk, or other printed cellulosic material is then added tothe reactor.

After a suitable period of time in the reactor, the mixture is droppedto a storage chest which is preferably equipped with a suitableagitator. If desired, water may be charged to the chest to reduce thesolid content of the mixture therein. The mixture from the chest is thendiluted to the solid content indicated hereinabove, and washed andthickened in a well known manner as, for example, by a Lancasterthree-stage washer and thickener equipped with a 45 mesh wire screen.The pulp may be thickened to about a 5 percent solid consistency, orbetween about a 3 to 8 percent solid consistency in this manner.Cocurrent or countercurrent washing, alone or in combination, may beused. The resulting pulp is then acidified to the pH indicatedhereinabove by addition thereto of a dilute solution of a suitable acid,as for example, alum, sulfuric acid, S0 and so forth. The resulting pulpmay be finally thickened and formed into a web. The number of thickeningand washing steps preceding the acidification step, it should beunderstood, is not critical, and the number of. such. treatments will begoverned largely by the type of equipment employed. Also, if desired,the pulp may be bleached, using a suitable bleaching agent, followingacidification. Ordinarily, however, bleaching is not required. When onlyacidification is used, the pulp need not be, and preferably is not,washed following acidification.

The nature of the invention will be made more clear from the followingexamples, which are exemplary of the mode of carrying out the de-inkingprocess already described. I

Example 1 City water is charged to a reactor, which is an eight footdiameter hydrapulper, arranged for batch operation, and equipped with ainch diameter rotor for operation at 247 rpm. by a HF. motor and oneinch diameter extraction blades. Based on the weight of newspaper, 1.6percent of an ethylene oxide adduct of dodecyl phenol and an equalamount of ethylene glycol are charged to the reactor and the admixtureagitated.

To the resulting solution is added about 5 percent by weight, based uponthe weight of the solution, of nonshredded, dry newspaper scrap andjunk.

Sodium hydroxide is added to raise the pH of the aqueous slurry to aboutpH 7.5.

Agitation is contained with stirring for about 25 min utes. The pulp isthen dropped to a chest, after which it is diluted with water to give amixture'comprising about 1 percent by weight of pulp. The pulp is thenthickened and washed by a Lancaster three-stage washer and thickenerequipped with a mesh Wire screen. The solid content of.

pulp drawn off the Lancaster machine is about 5.0 percent by weight. Thepulp is then acidified to a pH of 5.0 by addition of S0 gas. Followingacidification, the pulp is again thickened and formed into a web.

The pulp has a substantially white appearance and can readily be handledon conventional paper making machines to produce a paper web sheet.

Paper sheets prepared from the pulp following acidification have anaverage T.A.P.P.I. standard brightness of 58 to 62.

Example 2 Example 1 is repeated with the exception that an ethyleneoxide adduct of nonyl phenol is substituted for the ethylene oxidedodecyl phenol. Similar results are obtained.

Example 3 Example 1 is repeated with the exception that diethyleneglycol is substituted for ethylene glycol. Similar results are obtained.

Example 4 Example 1 is repeated with the exception that propylene glycolis substituted for ethylene glycol. Similar results are obtained.

Although in the examples the de-inking agents are added to the waterdirectly, it should be understood that the agents may also be introducedinto the water in association wtih the waste cellulosic material, as forexample, by spraying the waste material with the de-inking agents priorto introduction of the waste newspaper into the pulper or reactor.

Although in the examples the de-inking agents are semibatch process isindicated, it should be understood that the de-inking may be carried outusing a continuous process, as will be obvious to those skilled in theart.

The invention in its broader aspects is not limited to the specificcompositions, steps and methods described, but departures may be madetherefrom within the scope of the accompanying claims without departingfrom the principles of the invention and without sacrificing its chiefadvantages.

What is claimed is:

1. In a method of de-inking waste printed paper, the

6 improvement which comprises pulping waste printed paper in an aqueoussolution with a small effective deinking amount of a nonionic surfaceactive agent and a polyol, the nonionic surface active agentcorresponding to the formula wherein R represents the residue of analkyl phenol in which the total number of carbon atoms is between 7 and24, R represents hydrogen or lower alkyl, and n is an integer of from 2to 100, and the polyol being a compound having more than one hydroxyl(-OH) group, each of which is attached to separate carbon atoms of analiphatic skeleton, the weight ratio of nonionic surface active agent topolyol being between 10:1 and 1:10.

2. The method of claim 1 wherein the polyol is a member selected fromthe group consisting of glycols, glycerol, pentaerythritol,trimethylolethane, trimethylolpropane, 1, 2,6-hexanetriol, sorbitol,inositol and mixtures of the foregoing.

3. A composition of matter capable, when mixed in appropriate amountswith water and waste printed paper, of de-inking the waste printedpaper, said composition of matter consisting essentially of:

(a) a nonionic surface active agent corresponding to the formula whereinR represents the residue of an alkyl phenol in which the total number ofcarbon atoms is between 7 and 24, R represents hydrogen or lower alkyl,and n is an integer of from 2 to 100, and

(b) a polyol containing more than one hydroxyl group (-OH), each ofwhich is attached to separate carbon atoms of an aliphatic skeleton, theweight ratio of nonionic surface active agent to polyol being between1021 and 1:10.

4. A composition of matter as in claim 3 wherein the weight ratio ofnonionic surface active agent to polyol is between 2:1 and 1:2.

5. A composition of matter as in claim 3 wherein the polyol is selectedfrom the group consisting of glycols, glycerol, pentaerythritol,trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, sorbitol,inositol and mixtures of the foregoing.

6. A composition of matter as in claim 5 wherein the weight ratio ofsurface active agent to polyol is between 2:1 and 1:2.

7. The method of claim 1 wherein the nonionic surface active agentcorresponds to the formula R (CH CH -O--) -H wherein R is the residue ofalkyl phenol in which the total number of carbon atoms is between 7 and24.

8. A process for de-inking waste printed paper which comprises pulpingprinted cellulosic material in an aqueous solution comprising a nonionicsurface active agent and a polyol, the nonionic surface active agentcorresponding to the formula wherein R represents the residue of analkyl phenol in which the total number of carbon atoms is between 7 and24, R represents hydrogen or lower alkyl, and n is an integer of from 2to 100, and the polyol being a member selected from the group consistingof glycols, glycerol, pentaerythritol. trimethylolethane,trimethylolpropane, 1, 2,6-hexanetriol, sorbitol, inositol and mixturesof the foregoing, the weight ratio of nonionic surface active agent topolyol being between 10:1 and 1:10, the amount of printed cellulosicmaterial being below about 10% by weight of the aqueous solution, andthe amount of nonionic detergent and polyol being an effective de-inkingamount, the amount of each being between about 0.1 and 3 percent, basedupon the weight of the cellulosic material, continuing the pulping for asufiicient time to de-ink, and separating the resulting de-inked pulpfrom the aqueous solution.

9. The method of claim 8 wherein the aqueous solution has an alkalinepH.

10. The method of claim 9 wherein the pH of the pulp is reduced tobetween about 4.0 and 6.50 following wash- 11. The method of claim 10wherein the amount of printed paper charged to the pulper is betweenabout 4.0 and 6.0 percent by weight of the solution.

12. The method of claim 11 wherein the amount of nonionic detergent andpolyol is each between about 1 and 2.5

. v r q "s 7 percent, based upon the weight of the cellulosic material.13. The method of claim 8 wherein the weight ratio of nonionic surfaceactive agent to polyol is between 2:1 and 1:2.

References Cited UNITED STATES PATENTS 8/1962 Grossmann etal. 162 -53,051,610 3,072,521 1/ 1963 Samuelson et al. -1625 10 3,158,530 11/1964Anastasio 162-5 S. LEON BASHORE, Primary Examiner.

